The explosion occurred about 7 p.m. in a bathroom near Terminal 2, Gate 27. No injuries were reported.

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Normal operations resumed just before 9 p.m., officials said. Four departure flights between 9:45 p.m. and 10:40 p.m. PT were delayed and passengers on three arriving flights were delayed from claiming checked luggage because baggage handling operations were temporarily stopped.

The "dry ice bomb" was described as a plastic bottle with dry ice inside. An airport employee heard the explosion from the tarmac and discovered the object inside an empty, non-public restroom.

The Los Angeles Police Department's bomb squad arrived at the scene and investigated the incident. The investigation was transferred from the FBI to the Los Angeles Police Department Monday morning.

FBI officials said there were "no stated threats associated wtih the incident." Sources told NBC News that investigators suspect the bomb, found in a toilet, was intended as a prank.

"It's pretty stupid for people to do something like that," said passenger Sheil Ranmal.

No arrests were reported.

FBI spokeswoman Laura Eimiller released the following written statement:

"Earlier this evening, law enforcement and airport officials responded to a report of an explosion in an employee bathroom in Terminal 2 at Los Angeles International Airport. In a restricted area of the terminal (not accessible to the general public), responders found evidence of a plastic bottle containing dry ice.

"A chemical reaction caused the explosion. No injuries were reported and the area is being examined for evidence. As a precaution, the terminal was closed temporarily, however, has since been reopened. The FBI and partners with LAPD, LAX PD, LA Fire, CBP, TSA and other officials will investigate the incident to determine the individual or group responsible."

The incident bears some similarities to the commotion caused by a dry ice bomb left in a trash can at Disneyland's Toon Town earlier this year. In that case, part of the park was evacuated. No injuries were reported and a Disneyland employee was arrested for allegedly placing the object.